Helo,
New to this so bear with me. My pickup will drive fine for 4 or 5 miles, then the tow\haul will flash and it will drop out of gear. When slowing down, it either won't downshift or will downshift to first gear at any speed, Even at 60 mph. I can shut the key off and start the truck again and it will be fine for a while longer. New dex 6 fluid and filter, new line pressure solenoid. The truck has a 5.4L. Does anybody have a clue what's going on? It's pretty scary when it screws up so it's just sitting right now, but I have to have this truck moving asap. Thanks in advance!

 

Welcome to FTE kevo2569.

Have your truck scanned and see what error codes are coming from your transmission.

 

And don't take it to an auto parts store that reads codes for free. They don't have the right tool to read Ford transmission codes. You need either a good independent shop or a Ford dealer.

 

Recently changed my tranny fluid on my 08 and the last Dex6 bottle of tranny fluid I looked at said not to use where Mercon LV or SP is called for.

check it out.